Using a cell-free polysomal system obtained from 14-day old chicken embryonic leg muscle polysomes, we will attempt to: 1. study the synthesis and assembly of the troponin complex, the important regulatory protein in muscle; 2. study the role of membrane-bound polysomes in protein synthesis in muscle; and 3. characterize the cytoplasmic non-polysomal ribonucleoprotein (RNP) complexes recently observed by us in developing muscles. We hope to extend these studies as probes in understanding the molecular mechanisms involved in the differentiation of muscle cells in culture.